DESCRIPTION: In spite of the remarkable decline in the prevalence of Dental caries observed in the U.S. during the past 25 years, Dental caries continues to be the most common Dental disease and additional measures for the prevention and control of this disease are needed. The ability to detect Dental caries at an earlier stage of development would markedly facilitate the development of more effective measures for the prevention and control of this disease and their use in Dental practice. Conventional visual-tactile-radiographic procedures for caries detection are unable to detect the caries process until it has progressed through 300-500 microns of enamel and such lesions are difficult to reverse/remineralize with restorative procedures frequently required. Research during the past decade has demonstrated that a new technology, Quantitative Light Fluorescence (QLF) is not only capable of detecting the caries process much earlier but is able to quantify changes in the mineral content, i.e., demineralization and remineralization, as they occur in situ. This capability will allow Dental practitioners to: 1) identify early lesions reflecting caries risk prior to cavitation; 2) implement appropriate interventions to reverse the disease process at an earlier stage with more efficient outcomes; and 3) monitor the success (or failure) of the applied intervention measures. Nevertheless, the QLF instrumentation used for research is quite cumbersome and unacceptable for routine use in clinical Dental practice and in clinical research. This Phase I application proposes to redesign the QLF handpiece and conduct the necessary laboratory validation tests to assure the continued ability to detect very early lesions. To achieve these goals a team of engineers and Dental clinicians will redesign and reconstruct the hand-piece component of the QLF system to: a) reduce its bulk, weight, and shape in order to facilitate its use on posterior teeth, b) replace the current mirror attachment to prevent fogging and improve image quality, c) improve the level of illumination to prevent shadows; d) replace/revise the cumbersome video cables and light guide system; e) add the capability of obtaining white light images; and f) add a dehydration system to permit the clinician to determine the activity of the detected lesions. The resultant prototype hand-piece will then be evaluated in the laboratory to verify its functional ability for QLF examinations.